Management of foot rot (Sclerotium rolfsii Sacc.) of finger millet (Eleusine coracana L. Gaertn)
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Date
2013-11
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Navsari Agricultural University, Navsari
Abstract
Finger millet (Eleusine coracana (L.) Gaertn) is an
important millet crop. During the survey, occurrence of foot rot
disease in finger millet (cv. GN-4 and Local) was observed in
serious proportion inflicting heavy losses in south Gujarat.
Considering the seriousness of the disease, the present
investigation was carried out on various aspects to generate
scientific information on this important pathological problem and
to develop suitable management strategies to prevent the crop
losses.
The symptoms of the disease were recorded from
infected fields. The initial symptom of the disease was appeared in
the field 25 to 30 days after transplanting. Initially, symptoms
started at collar region with softening and browning of the tissues
as spot. This spots progressed and produced dark brown legion
with concomitant shrinking on the crown. Infected leaves of the
plant were dull in appearance, dropping towards the ground and
plants became pale green or chlorotic and got stunted. Root
system was poorly developed and cortex was rotted. Such plants
finally were wilted and dried. White fan like mycelial growth was
observed between basal portion and sheaths of the stem. Later
mustard seed like, dark brown sclerotia were observed on the
basal portion of the stem, inside the leaf sheaths as well as the
soil near to the collar region.
The isolation from infected plant parts revealed the
association of Sclerotium spp., which was identified after the
cultural and morphological studies as Sclerotium rolfsii Sacc. This
was also confirmed by Indian Type Culture Collection (I.T.C.C.),
Division of Plant Pathology, I.A.R.I., New Delhi as Sclerotium rolfsii
Sacc. The pathogenicity of the fungus was confirmed by soil
inoculation, collar region inoculation at seedling stage and
seedling root dip inoculation methods with positive results. Out of
these methods, soil inoculation method was found more efficient
in proving the pathogenicity.
The foot rot was found in more severe proportion on
popular variety GN-4 (21.44%) than local (6.22%) in major finger
millet growing area of Dang and Valsad districts of south Gujarat.
Losses due to the foot rot was estimated up to 27.40 per cent in
grain yield and 23.31 per cent in fodder yield.
The infection of foot rot in finger millet was started
during second fortnight of August and attained its peak on
completion of major rainfall i.e. after 36th MSW. The disease was
more progressive during 36th to 38th MSW in both the years when
soil temperature was from 280C to 290C, rainfall from 2.70 to
26.10 mm and soil moisture from 19.64 to 26.82 per cent.
Correlation of foot rot incidence with soil and weather
parameters indicated that all the parameters jointly played an
important role in the development of the foot rot. The multiple
regression equation [Ŷ = 32.2222 + 0.3818 (X1) - 0.0291 (X2) -
1.3721 (X3) – 1.1206 (X4) where Ŷ= Predicted disease incidence, X1
= Soil temperature, X2 = Rain fall, X3 = Rainy days and X4 = Soil
moisture] was developed for the forecasting (R=0.99).
Studies on interaction of known antagonists with the
pathogen by dual culture method indicated that Trichoderma
harzianum (Navsari isolate), Pseudomonas fluorescens (Waghai
isolate) and T. viride (Navsari isolate) were found strong
antagonistic to S. rolfsii.
Organic extracts tested against S. rolfsii revealed that,
neem cake and farm yard manure (FYM) had strong inhibitory
effect on the growth of S. rolfsii. In vitro evaluation of
phytoextracts, neem leaf extract (Azadirachta indica Juss.) proved
excellent in inhibiting the growth of the pathogen.
Amongst the 14 genotypes of finger millet screened
against the foot rot disease, genotypes PR202 and VL149 showed
moderately resistant reaction against the disease. The rest of the
varieties/genotypes proved susceptible. Only, GN-4 exhibited
highly susceptible reaction against the foot rot. In case of grain
yield, GPU 67, KMR 204 and L5 were high yielding varieties.
In Integrated Diseases Management (IDM) trial, seed
treatment with P. flourescens + T. viride each @ 5 g/kg or seed
treatment with T. viride @ 10 g/kg proved better for the disease
management as well as for getting higher grain and fodder yield.
Description
Keywords
diseases, millets, fungi, planting, biological phenomena, sowing, farmyard manure, application methods, biological development, seed treatment